Waste Tungsten Recycle Sodium Perchlorotungstate by Ion Exchange Method

Industrial wastes containing heavy metals such as copper, nickel, cobalt, manganese, tungsten, and other heavy metals are treated by proper methods, and the valuable components of the industrial waste can be recycled, the harmless and resource utilization of industrial waste can be realized. At present, the method of metal recycling for such industrial wastes is usually used by alkali leaching, using sodium hydroxide or sodium carbonate as leach agents. The tungsten is leached under normal pressure or pressure condition, and tungsten is separated from other metals, and the tungstate solution is obtained by ion exchange and enrichment in the next step, the alkali leaching residue is then soaked in acid. Removal of impurities, separation and purification of copper, nickel, cobalt and manganese products.

For the recovery of tungsten in alkaline sodium tungstate leaching solution, the method of ion exchange is usually used in wet process recovery treatment, but ion exchange has the disadvantages of low recovery rate of tungsten, high cost and large amount of waste water. The key to solve the technical problem is to provide a method of separation and recovery of tungsten in sodium perchlorotungstate solution, The method includes the following steps:

(1) The content of various elements in the leaching solution of sodium perchlorotungstate is analyzed and tested. The results are as follows: Cu1 2.0mg/L、Ni 7.5.mg/L、Co 0.5mg/L、Mn 0.3mg/L、Zn 4.2mg/L、Fe 0.7mg/L、Ca 1.1mg/L、Mg 1.0mg/L、Al 1.7mg/L、S 2-20mg/L、W 40.9g/L、Cl-12.0g/L和OH^-16.4g/L.

(2) The 5000mL sodium perchlorotungstate solution is taken and the pH of sodium tungstate solution is adjusted to 13 with hydrochloric acid. The saturated calcium chloride solution is used to sink the tungsten, the dosage of calcium chloride is CaCl₂:W=1.25:1 (mole ratio), the temperature is 65°C, the time is 4h, the calcium tungstate precipitation and the mother liquid of the tungsten are obtained.

(3) The obtained tungsten concentrate was adjusted by pH to 7 with hydrochloric acid and purified by sodium chloride crystallization.

(4) Sodium tungstate was decomposed to sodium tungstate with sodium tungstate in sodium hydroxide solution at normal pressure to obtain sodium tungstate solution. The concentration of OH^- in the solution was 1.5g/L, the decomposition temperature was 85°C, time for 5h. The molar ratio of sodium phosphate to calcium tungstate is 1:1.20, and the content of all elements in the sodium tungstate solution is Cu2.2mg/L, Ni0.5mg/L, Co0.7mg/L, Mn1.0mg/L, Zn1.8mg/L, Fe0.9mg/L, Ca0.8mg/L, Mg0.6mg/L, Al2.5mg/L, S2^-15mg/L respectively. It can meet the requirements of ion exchange in tungstate solution.

The sodium tungstate solution obtained by the alkali decomposition process is treated by ion exchange with conventional ion exchange method. The high purity ammonium para tungstate can be obtained after the solution is desorbed by evaporation crystallization. The recovery rate of W was 99.5% during the whole process.

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